Mortality of Epilepsy in Developed Countries: A Review

Mortality in people with epilepsy has been studied in many different populations. In population-based incidence cohorts of epilepsy with 7-29 years follow-up, there was up to a threefold increase in mortality, compared to the general population (standardized mortality ratios SMR ranged from 1.6 to 3.0). When studies include selected epilepsy populations where patients with frequent and severe seizures are more common, the mortality is even greater. Relative survivorship (RS) following the diagnosis of epilepsy was 91%, 85%, and 83% after 5, 10, and 15 years, respectively. In a population with childhood-onset epilepsy, RS was 94% and 88% after 10 and 20 years. The level of increased mortality is affected by several factors. In idiopathic epilepsy where the causes of seizures are unknown, the results are conflicting. There was no significant increase in mortality in studies from Iceland, France, and Sweden, a barely increased risk in a study from the United Kingdom, and a significantly increased risk in a study from the United States. In contrast, all studies report a significant increased mortality in remote symptomatic epilepsy (standardized mortality ratios SMRs ranging from 2.2 to 6.5). The highest mortality is found in patients with epilepsy and neurodeficits present since birth, including mental retardation or cerebral palsy (SMRs ranging from 7 to 50). Mortality is also affected by age, with the highest SMRs in children, the combined effect of low mortality in the reference population, and high mortality in children with neurodeficits and epilepsy. The highest excess mortality is found in the elderly, > or =75 years. A pronounced increase in mortality is found during the first year following the onset of seizures due to underlying severe diseases. The increased mortality remains in different studies 2-14 years following diagnosis. Most of the factors responsible for the increased mortality are related to the underlying disorder causing epilepsy with pneumonia, cerebrovascular disease, and neoplastic disorders (risk remains elevated when primary brain tumors are excluded), as the most frequently recorded causes. The most common direct seizure-related cause of death in adolescents and young adults is sudden unexpected death, which is 24 times more common than in the general population.